http://swrc.ontoware.org/ontology#Article Spatiotemporally continuous temperature monitoring using optical fibers (Loop 2) for ground surface and subsurface with various vegetations on a flat area with slope surface in the internal Alaska from 2016 to 2019 en fiber-optic sensor permafrost boreal forest temperature We measured spatiotemporally continuous surface temperature using 5.4 km of fiber-optic cable with a distributed temperature sensing system at an observation site in interior Alaska. The study area is covered by diverse plant ecosystems in the Arctic region, including black spruce and open moss. The spatial and temporal resolutions were 0.5 m and 30 min, respectively. About 4.4 km of the cable was installed in a flat area at an elevation of approximately 210 m above sea level (a.s.l.), and the last 1 km section was installed along a slope facing northwest, with the highest point reaching approximately 410 m a.s.l. Four quadrats with different vegetation coverages were set in a flat area. The sensor cables ran along each side (approximately 30 m) and one diagonal of the square at the surface and at the depth of 0.2 m below the surface to measure the temperature variations in the active layers. The measurements spanned 985 days from July 13, 2016, to February 25, 2019, of which measurements were made on 893 days covering various seasons, including snow cover, snow melt, and warm weather. Polar Data Journal 9 14-29 2025-04 National Institute of Polar Research 2432-6771 https://doi.org/10.17592/001.2024041202|Original Data Atmospheric science/Climatology Glaciology Terrestrial biology